Embodiments of the present invention provide a method and system for rendering polygons having abutting edges. Embodiments of the present invention provide fast and efficient real-time 3-D graphics rendering while ensuring foreground objects are properly anti-aliased against a background in order to preserve image quality.
In one embodiment, the present invention is implemented as a method for rendering adjacent polygons in a GPU. The method includes determining when a first polygon and a second polygon have an abutting edge (e.g., as in a case where multiple polygons are used to construct an object). If an abutting edge exists, a majority status is assigned to a pixel on the abutting edge. A first color of the first polygon or a second color of the second polygon is then allocated to the pixel in accordance with the majority status. In a typical implementation, at least one edge of the first polygon or the second polygon other than the abutting edge is anti-aliased with respect to a background color. The present embodiment saves the cost of the unnecessary blending operations by use of the majority status. The majority status can be determined by determining whether the first polygon or the second polygon covers a center of the pixel.
In one embodiment the abutting edge is determined by detecting when the first polygon and the second polygon have common vertices. Alternatively, the abutting edge can be determined by parsing a list of vertices describing a plurality of polygons (e.g., triangle strip, etc.), or by detecting a winged edged polyhedron.